feat(city): digital net overlay

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

crates/city/src/render/mod.rs

@@ -2,6 +2,7 @@
 
 pub mod lighting;
 pub mod minimap;
+pub mod overlay;
 pub mod style;
 pub mod tileset;
 pub mod traffic;

crates/city/src/render/overlay.rs

@@ -0,0 +1,203 @@
+//! The digital overlay: Net nodes, subnet outlines and links drawn over the physical map.
+
+use crate::anim::effects::pulse;
+use crate::render::Rgb;
+use crate::render::style::StylePack;
+use crate::render::viewport::{Overlay, tile_to_screen};
+use citygen::pathing::bresenham;
+use citygen::{City, NodeId, NodeKind, Pos, StratumKind, SubnetOwner};
+use ratatui::buffer::Buffer;
+use ratatui::layout::Rect;
+use ratatui::style::Color;
+
+/// Signal cyan used for everything digital.
+pub const SIGNAL: Rgb = Rgb(0, 255, 200);
+
+/// Net nodes as wireframe glyphs; the focused node's subnet lights up with its links.
+pub struct Digital {
+    pub enabled: bool,
+    pub focus: Option<NodeId>,
+}
+
+impl Digital {
+    /// Index into the style's `net` glyph set for a node kind.
+    fn glyph_index(kind: NodeKind) -> usize {
+        match kind {
+            NodeKind::Terminal => 0,
+            NodeKind::Server => 1,
+            NodeKind::Backbone => 2,
+            NodeKind::DataVault => 3,
+            NodeKind::Ice => 5,
+            _ => 4,
+        }
+    }
+
+    pub fn node_under(city: &City, stratum: StratumKind, p: Pos) -> Option<NodeId> {
+        city.net.node_at(stratum, p).map(|n| n.id)
+    }
+}
+
+impl Overlay for Digital {
+    fn draw(
+        &self,
+        city: &City,
+        stratum: StratumKind,
+        origin: Pos,
+        area: Rect,
+        tick: u64,
+        buf: &mut Buffer,
+        style: &StylePack,
+    ) {
+        if !self.enabled {
+            return;
+        }
+        let glyphs = &style.glyphs.net;
+        let focus_subnet = self.focus.map(|id| city.net.node(id).subnet);
+
+        // Faint outline on every building that owns a subnet.
+        for sn in &city.net.subnets {
+            let SubnetOwner::Building(b) = sn.owner else {
+                continue;
+            };
+            let building = city.building(b);
+            if !building.span.contains(stratum) {
+                continue;
+            }
+            let hot = focus_subnet == Some(sn.id);
+            for p in building.footprint.border() {
+                if let Some((sx, sy)) = tile_to_screen(area, origin, p) {
+                    let c = &mut buf[(sx, sy)];
+                    let bg = match c.bg {
+                        Color::Rgb(r, g, b) => Rgb(r, g, b),
+                        _ => Rgb(0, 0, 0),
+                    };
+                    let strength = if hot { 0.5 } else { 0.18 };
+                    c.set_bg(bg.mix(SIGNAL, strength).to_color());
+                }
+            }
+        }
+
+        // Links of the focused subnet, as dotted lines between anchors on this stratum.
+        if let Some(sn) = focus_subnet {
+            for link in &city.net.links {
+                let a = city.net.node(link.0);
+                let b = city.net.node(link.1);
+                if a.subnet != sn && b.subnet != sn {
+                    continue;
+                }
+                if a.anchor.0 != stratum || b.anchor.0 != stratum {
+                    continue;
+                }
+                for p in bresenham(a.anchor.1, b.anchor.1) {
+                    if city.net.node_at(stratum, p).is_some() {
+                        continue;
+                    }
+                    if let Some((sx, sy)) = tile_to_screen(area, origin, p) {
+                        buf[(sx, sy)]
+                            .set_char('·')
+                            .set_fg(SIGNAL.scale(0.8).to_color());
+                    }
+                }
+            }
+        }
+
+        let glow = 0.6 + 0.4 * pulse(tick, 40);
+        for n in city.net.nodes_on(stratum) {
+            let Some((sx, sy)) = tile_to_screen(area, origin, n.anchor.1) else {
+                continue;
+            };
+            let g = glyphs[Self::glyph_index(n.kind) % glyphs.len()];
+            let hot = focus_subnet == Some(n.subnet);
+            let fg = if hot {
+                Rgb(255, 255, 255)
+            } else {
+                SIGNAL.scale(glow)
+            };
+            buf[(sx, sy)].set_char(g).set_fg(fg.to_color());
+        }
+    }
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::render::style::StylePack;
+    use crate::render::viewport::MapView;
+    use citygen::{GenParams, Generator, NodeKind, Pos, SizePreset, StratumKind};
+    use ratatui::Terminal;
+    use ratatui::backend::TestBackend;
+    use ratatui::widgets::Widget;
+
+    #[test]
+    fn overlay_draws_nodes_on_current_stratum_only() {
+        let c = Generator::run(GenParams {
+            seed: 8,
+            size: SizePreset::Custom { w: 80, h: 40 },
+            districts: 4,
+            ..Default::default()
+        })
+        .unwrap();
+        let s = StylePack::load().unwrap();
+        // A server that is alone on its tile (backbones may share a server's anchor).
+        let node = c
+            .net
+            .nodes
+            .iter()
+            .find(|n| {
+                n.kind == NodeKind::Server
+                    && c.net.nodes.iter().filter(|m| m.anchor == n.anchor).count() == 1
+            })
+            .unwrap();
+        let (k, p) = node.anchor;
+        let mut t = Terminal::new(TestBackend::new(80, 40)).unwrap();
+        let draw = |t: &mut Terminal<TestBackend>, stratum, focus| {
+            t.draw(|f| {
+                MapView {
+                    city: &c,
+                    stratum,
+                    origin: Pos::new(0, 0),
+                    tick: 0,
+                    style: &s,
+                    vis: None,
+                    overlays: &[&Digital {
+                        enabled: true,
+                        focus,
+                    }],
+                    cursor: None,
+                }
+                .render(f.area(), f.buffer_mut())
+            })
+            .unwrap();
+        };
+        draw(&mut t, k, None);
+        assert_eq!(t.backend().buffer()[(p.x as u16, p.y as u16)].symbol(), "◆");
+        let other = StratumKind::PHYSICAL
+            .iter()
+            .copied()
+            .find(|s| *s != k)
+            .unwrap();
+        draw(&mut t, other, None);
+        assert_ne!(t.backend().buffer()[(p.x as u16, p.y as u16)].symbol(), "◆");
+        draw(&mut t, k, Some(node.id));
+        assert_eq!(Digital::node_under(&c, k, p), Some(node.id));
+        assert_eq!(Digital::node_under(&c, k, Pos::new(-1, -1)), None);
+        let off = Digital {
+            enabled: false,
+            focus: None,
+        };
+        t.draw(|f| {
+            MapView {
+                city: &c,
+                stratum: k,
+                origin: Pos::new(0, 0),
+                tick: 0,
+                style: &s,
+                vis: None,
+                overlays: &[&off],
+                cursor: None,
+            }
+            .render(f.area(), f.buffer_mut())
+        })
+        .unwrap();
+        assert_ne!(t.backend().buffer()[(p.x as u16, p.y as u16)].symbol(), "◆");
+    }
+}